1. Field of the Invention
The present invention relates to semiconductor packages and fabrication methods thereof, and, more particularly, to a semiconductor package having an electromagnetic interference (EMI) shielding function and a fabrication method thereof.
2. Description of Related Art
Along with the miniaturization and system integration of electronic products, various electronic elements such as one or more chips and passive components are integrated in a package to form a system in package (SIP). However, electromagnetic interferences can easily occur between adjacent electronic elements. Particularly, when more and more electronic elements are integrated in a package and arranged closer and closer to one another, the EMI problem has become more and more serious.
FIG. 1A shows a semiconductor package la as disclosed by U.S. Pat. No. 7,049,682. A plurality of electronic elements 11a and 14a are disposed on a substrate 10a in a side by side manner and electrically connected to the substrate 10a. Then, an encapsulant 15a is formed on the substrate 10a to encapsulate each of the electronic elements 11a and 14a, thus forming a plurality of packages 12a. Further, a plurality of lid members 13a are provided to cover the semiconductor packages 12a, respectively, so as to prevent EMI from occurring between the electronic elements 11a and 14a. 
However, since the electronic elements 11a and 14a are arranged in a side by side manner, when the number of the electronic elements 11a and 14a increases, the area of the substrate 20 must be increased correspondingly in order to accommodate the electronic elements 11a and 14a, thus increasing the fabrication cost and the size of the overall structure.
Further, the use of the lid members 13a also increases the fabrication cost.
To overcome the above-described drawbacks, electronic elements can be vertically stacked on one another to thereby save space on the substrate. FIG. 1B shows a semiconductor package lb as disclosed by U.S. Pat. No. 8,049,119. A substrate 10b having a first shielding layer 100 therein is provided, and a chip 11b is bonded to the substrate 10b in a flip-chip manner. Further, an electronic element 14b having a second shielding layer 140 formed on a bottom surface thereof via a sputtering process is stacked on the chip 11b, and the first and second shielding layers 100 and 140 are electrically connected through a conductive adhesive 13b to thereby prevent EMI from occurring between the chip 11b and an external electronic device. Then, an encapsulant 15b is formed via a molding process to encapsulate the electronic element 14b, and an opening 150 is formed in the encapsulant 15b to expose a portion of the surface of the electronic element 14b for another electronic element to be disposed thereon.
However, the sputtering process for forming the second shielding layer 140 involves a high fabrication cost.
In addition, a mold used in the molding process must be designed according to the size of the opening 150, and hence the same mold cannot be applied to electronic elements 14b of different sizes. As such, the fabrication cost is greatly increased.
Therefore, there is a need to provide a semiconductor package and a fabrication method thereof so as to overcome the above-described drawbacks.